Method of forming seals and terminals for electric apparatus.



No. 866,801. PATENTED SEPT. 17, 1907.

H. N. POTTER.

APPLICATION FILED NOV. 19,1903.

METHOD OF FORMING .SEALS AND TERMINALS FOR ELECTRIC APPARATUS.

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To all whom it may concern:

7 in the use of such material for such purposes has been that no electric conductor has hitherto been found a of the United States, and a resident of New UNITED STATES" PATENT OFFICE.

HENRY NOEL POTTER, OF NEW ROCHELLE, NEW YORK,

ASSIGN OR TO COOPER HEWITT ELEC- 'TRIO COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

warrior) or lira-866,301.

FORMING SEALS AND TERMINALS FOR Specification of Letters Patent.

ELECTRIC Arrsnsrus.

Patented Sept. 17, 1907.

Application filed November 19,1903. Serial No- 181,756.

a citizen Rochelle, have inin Meth- Be it known that I HENRv'NonL Po'r'rnn,

county of Westchester, State of New York, vented certain new and useful Improvements ods of Forming Seals and Terminals for Electric Apparatus, of which the following is a specification.

It has heretofore been proposed to employ quartz as an inclosing chamber for various electrical and other devices whereinits chemical and optical properties render it more advantageous than glass. One diflicul'ty which will form therewith a tight seal or conductor for leading electric current through the walls of the chamber. The nearest approach to this has been with metallic iridium which is refractory enough but which has an expansion coefficient differing sufliciently from quartz to prevent the seal remaining tight when cooled to ordinary temperatures. A seal made of iridium requires in addition an application of shellac or similar material to render it tight and consequently a vessel so made could not be heated in the region of the seal to temperatures sufiiciently high to adapt it for many uses,

especially for those which require a permanent high practicable for permanent uses.

I have discovered that silicon in its so-called metallic.

state has all the properties which adapt it for use as a seal in quartz vessels, and that with metallic silicon such seals can be made which are tight and by means of which current can be caused to pass through the wall of the 'vessel in practical quantities, and which seals are not injured bybeing heated to ared heat or even higher. The expansion coeflicient of metallic silicon seems to be approximately that of silica. It is further not oxidizable even at a white heat in the absence of such gases as carbon dioxid, for instance.

In practice I find an excellent way is to produce the metallic silicon in the form of a round rod or wire which can be readily done by grinding on an emery, wheel, and slipping the said rod within a tube of quartz so that the quartz tube projects beyond the rod of silicon. Ii then, the quartz be heated externally opposite the silicon rod in an oxy-hydrogen flame, the rod can be caused to melt and it will then wet and adhere to the silica and .will not separate from the latter when cooling. If it is further desired to expose the silicon the silica may then be removed by grinding or any other appropriate way 'and contact made with the silicon either by welding venting its making good electrical contact with the metals other than mercury may be readily used as a source of conducting vapor. Further, the quartz is dissolving in very dilute hydrofluoric acid. This acid will, of course, also attack the vessel of quartz, but the oxid film is so extremely thin as to be iridescent and it is almost instantly removed, so that the injury to the quartz vessel is negligible.

In case it is desired to produce the seal without the slightest danger of oxidation or a combination with any flame gases which may enter the tube, I find it entirely practicable to pass a slow current of inert gas such as hydrogen through the vessel during the period when the seal is being formed. This insures that the silicon is surrounded with an inert gas up to the instant of wetting the silica and also that the inner end of the silicon shall remain unchanged. 4

Metallic silicon is a good conductor of electricity of about the order of carbon, but has an advantage over carbon in that it is not porous; that it can be melted and cast into convenient preliminary shapes; that it does not 7 5 oxidize in air, even at white heat, and that it can be fused directly to platinum and other metals. In the case of metals likely to oxidize, a zflux such as borax .may be used with success. It is advantageous, however, to select as a metal one having a small coeflicient of expansion with change of temperature. I have found a goodmaterial to be nickel steel containing approximately 36.4 per cent of nickel,-this material having the least known coefficient of expansion among metals and being known as the Guillaume alloy.

I may mention as one very important use of this invention the application of it to the so-called Cooper Hewitt vapor lamps andother vapor devices. In the case of a lamp, the use of quartz is advantageous in that the latter is transparent to ultra-violet rays which have valuable therapeutic and other properties and for which glass is opaque. 'Further, lamps constructed of quartz can be operated at temperatures which are not permissible with glass of any kind, and, therefore,

more inert to chemical attack than glass, .and such metals as antimony, bismuth and lead in a melted 0r, gaseous state do not attack quartz. There is also an advantage in the use of quartz for mercury vapor devices in that the current density can be pushed far beyond what is possible in glass with attendant advantages. i

In the accompanying drawings which illustrates an application of the invention; Figure 1 shows a process of sealing the silicon to the quartz, and Fig. 2 illustrates an application of the invention to a Cooper Hewitt mercury vapor lamp.

Referring to the drawings, 1 represents a quartz tube; 2 represents a plug of silicon inserted loosely therein; 3

represents sueh, for instance, as an oxy-hydrogen flame.

of inert gas. sueh as hydrogen, is illustrated at 4. This gas is passed through the. tube 1, while sullieient heat is applied to melt the silieon and fuse it to the siliea. It should he stated, however, that the proeess of passing the inert gas through the tube is not; essential.

In Fig. 2, 5 represents the Wall of it lnerenry vapor lamp composed of silien or quartz. (l and 7 represent; leading-in Coiltlttetors ofsilit-on; 8 represents a solid eleetrode of any suitable (-ha'raet er, which is here shown as being attaehed to the inner surf-aetof. the leading-in eonduetor (i hy a (-onduetor 9. An exterior eonduetor. it), is likewise fastened to the exterior surface of the lending-in eonduetor ti. These. two eonduetors may he of platinum, nickel steel, or other suit-.thle material and fused directly to the slli('oti. In like manner. the eonduelor l'l may l)t sealed to the lending-in eonduetor 7, and at l2 1 huve illustrated a small quantity of mereury or other lluid conduetor from which the vapor 0011- 1 ductor is derived.

1 State ot New York.

stated that other materials than mercury may be employed in this ehamher l'or affording a eondueting path. in a divisional applit-ation tiled on the llth day of January, 1904, ('lztiiltS are made upon theapparatus herein.

I (l-aim as my invention:

1. The method at termin a silicon and quartz glass. which tm mer within the latter.

:2. The method of produeing a lending-in eonduetm' for eleetrienl derives. \\'lllt'll eonsists in fusing into the walls of a quartz glass ehamher a set-t ion of silieon.

It. The method of t'usin silieon to siliea. which eonsists in heatingthe joint to a temperature sntlieient to use the silieon in an inert gas.

net-ween metallic in fusing the sea I eonsi sts 4. The method of sealing silienn within a tube of silien,

\\lll('ll eonsists in passing an inert gas through the tube, and fusing the silit-on out of eontaei with gases active relative to it.

Signed :tt New York. in the eounty of NeW York, and this eighteenth day of November,

HENRY NOEL POTTER.

Witnesses Wu. H. (.APEL. (molten II. STOCKBRIDGE. 

